The present invention relates to the manufacture of sheathing for tubular electrodes for storage batteries.
Sheaths of this nature are known which comprise a fibrous inert material, on the outside of which there is disposed a thermoplastic material in the form of a net, perforated foil or the like. The sheath materials are delivered continuously over a stationary mandrel, during production and are joined together to form a tubular sheath as described for instance in U.S. Pat. Nos. 3,725,130 and 2,912,043.
In copending and commonly assigned U.S. application Ser. No. 533,499 filed Dec. 1, 1974, and Ser. No. 664,997 filed Mar. 8, 1974, methods are described for the manufacture of such a sheath. According to such methods, the fibrous material is heated before the thermoplastic material is delivered. Thus, there is produced, through contact of the materials, at least a local softening or melting of the thermoplastic material, so that a joint can be formed between the two materials. The process of the present invention is suitable both for such a method and for other methods where there is no preheating of the fibrous material.
It is an object of the present invention to provide a novel method for making electrode sheaths.
It is another object of the invention to provide such a method which minimizes deformation of the thermoplastic material.
It is another object of the present invention to provide novel apparatus for forming a tubular electrode sheath.